TINA/Spice/TM4C123GH6PM: USB Mode Device Connection

Alberto Stolowich

Part Number: TM4C123GH6PM
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Hi,

I have configured in the MCU the USB in device mode, I have the following doubt. According to data sheet PB1 / USB0VBUS it is + 5V not tolerant, but on the schematic page it is connected directly to VBUS of the USB connector (+ 5V). So I have two alternatives:

1) Disable VBUS monitoring (eUSBModeForceDevice) and sense the VBUS with another 5V tolerant pin.

2) Activate the VBUS monitoring (eUSBModeDevice) send PB1 to + 5V. In this case I would like to know what I recommend and how it would be the schematic from the pin to the USB connector, ie how to protect the pin from the current and the +5V.

Thanks and regards!

over 8 years ago

0 Ralph Jacobi over 8 years ago

TI__Guru*** 135355 points

Hello Alberto,

I looked at the datasheet and I didn't see anything which indicates PB1/USB0VBUS is not +5V tolerant. Can you please direct me to the section(s) which gave you this impression so I can review them and provide feedback or an explanation?

0 Alberto Stolowich over 8 years ago in reply to Ralph Jacobi

Prodigy 60 points

Tiva™ TM4C123GH6PM Microcontroller
DATA SHEET

0 Ralph Jacobi over 8 years ago in reply to Alberto Stolowich

TI__Guru*** 135355 points

Hello Alberto,

Okay, thank you for providing the Section with the lines in question. For those pins, the GPIO mode of the IO is not 5V tolerant. However, when used as USB pins the 5V can be applied to the PB1 pin. This does mean you should ensure that the PB1 pin is set for USB functionality and not GPIO functionality before that voltage is applied though.

For further details on that and suggestions about how to correctly handle this pin, please see Section 4.1.1 of the System Design Guidelines: www.ti.com/.../spma059.pdf

0 Alberto Stolowich over 8 years ago in reply to Ralph Jacobi

Prodigy 60 points

Thanks, it's what I needed!

Regards, Alberto.-

0 Alberto Stolowich over 8 years ago in reply to Ralph Jacobi

Prodigy 60 points

The doubt arose on the basis that in a development that was doing in the launchpad everything worked well (bypassing R25 and R29), when the prototype was developed I connected it to a Notebook with USB3.0 and the prototype was burned. We are trying to find out what actually happened and if you can give us some advice about it.

Thanks and Regards! Alberto.-

0 Ralph Jacobi over 8 years ago in reply to Alberto Stolowich

TI__Guru*** 135355 points

Hello Alberto,

Depending how 'burned' that prototype is, I'd be suspicious of board layout above all else.

That sort of issues sounds pretty severe (unless exaggerated), possible there was an unintended short maybe?

You may want to review LaunchPad schematic here: www.ti.com/.../spmu296.pdf

And Design Guidelines here (Section 4.1 has a lot on USB): www.ti.com/.../spma059.pdf

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TINA/Spice/TM4C123GH6PM: USB Mode Device Connection